Biodiversity allows the ecosystem to carry out important functions (Click "learn more" to learn more about ecosystem functions). Alarmingly, scientists have discovered that recent declines in biodiversity have been accompanied by increases in infectious disease.

What is biodiversity?

It is a measure of the amount of variation of life in an ecosystem, community or other defined area.
There are two main components to biodiversity, species richness and composition.

1. Species richness is the number of different species present.
The two communities of fish to the left have different species richness.

The one on the right is more diverse because it contains more unique species.

2. Composition is the relative abundance of each species, also called evenness.
These two fish communities have different compositions (evenness). Composition is measured in relative abundance of individual species. The composition of the community on the right for example is 82.5% orange fish, 8.25%yellow fish and 8.25% green fish.

Both aspects of biodiversity, species richness and species composition, can influence how ecosystems function.
Researchers in the Mitchell Lab at UNC Chapel Hill are trying to understand the relationship between biodiversity and infectious diseases.